Semiconductor lasers or light emitting diodes are examples of conventional semiconductor light emitting elements (see e.g. Patent Document 1 below). Semiconductor light emitting elements can provide in general high luminance with less power consumption, thereby making a suitable light source for a liquid crystal display device, for example.    Patent Document 1: JP-A-2003-243773
FIG. 10 shows a conventional semiconductor light emitting element. The illustrated light emitting element X includes a substrate 101, on which an n-GaN layer 102, an active layer 103 and a p-GaN layer 104 are laminated. The n-GaN layer 102 and the p-GaN layer 104 are covered by an insulating layer 107. The insulating layer 107 is made of e.g. SiO2 and formed with two openings 107a. The openings 107a expose part of the n-GaN layer 102 and p-GaN layer 104. A wiring 108 is connected to each of the n-GaN layer 102 and the p-GaN layer 104 via the opening 107a. The wiring 108 includes an Ni layer 108a contacting the n-GaN layer 102 or the p-GaN layer 104, and an Au layer 108b formed on the Ni layer 108.
The light emitting element X has the following problems. In manufacturing the light emitting element X, the openings 107a are formed by etching the insulating layer covering the n-GaN layer 102 and the p-GaN layer 104. This etching damages the n-GaN layer 102 and the p-GaN layer 104. As a result, the electrical resistance at the interface between each of these layers and the wiring 108 increases, so that the drive voltage of the light emitting element X becomes unduly high.
As one of the measures against this problem, it may be considered to form a relay electrode (not shown) made of e.g. Au in each of the openings 107a and then form the wiring 108. In this case, good electrical conduction is expected to be established between the n-GaN layer 102 or the p-GaN layer 104 and the wiring 108 by the relay electrode.
However, this arrangement causes another problem. That is, when the wiring 108 is formed at a high ambient temperature, Au may diffuse from the relay electrode into the insulating layer 107. As a result, at least part of the insulating layer 107 becomes conductive, which increases the leakage current.